1. Technical Field
The present invention relates to manufacturing methods for axially symmetric light-emitting diodes, and more particularly, to a manufacturing method for an axially symmetric light-emitting diode assembly useful to improve the light patterns of LED lamps having multiple light-emitting areas.
2. Description of Related Art
The current trend in LED (light-emitting diode) development goes toward high power light-emitting diodes, which have enhanced overall luminance by packaging plural light-emitting diodes with one substrate. In the packaging process, since the light-emitting diodes are separated by miner intervals, silver paste or solder applied to fix the light-emitting diode on the substrate tends to overflow and cause short circuit among the light-emitting diode. Thus, one known solution is to form multiple light-emitting areas on a single light-emitting diode chip, so as to eliminate problems related to overflowed silver paste or solder while providing improved light extraction efficiency.
For example, U.S. Pat. No. 6,869,812 B1 titled “High power AlInGaN based multi-chip light emitting diode” has disclosed a method for fabricating a light-emitting diode chip, which comprises steps of: providing a transparent substrate; forming at least one active area on the substrate; and cutting the substrate to form at least one light-emitting diode chip with an active area.
The aforementioned prior-art technology improves the overall light extraction efficiency by forming plural active areas with elongated geometry on a transparent substrate, wherein each of the active areas is provided with light-emitting diodes. However, the LED chip of U.S. Pat. No. 6,869,812 B1 has its light pattern restricted by the elongated shape of the active areas and thus suffers from uneven light distribution and asymmetric light pattern.
The problems brought by the elongated geometry of the active areas to the light-emitting diode chip also include limiting the optimal usage of the substrate space. In addition, active areas of such elongated or similar geometry when arranged on the substrate are asymmetric, thus failing to provide a symmetric light pattern.